Synthesis of (+)-4-methoxy-substituted Ketomorphians to be evaluated as antitussive agents and to afford information regarding the existence of a possible antitussive receptor has been continued. A variation of a synthetic scheme developed ealier has afforded (+)-4-methoxy-morphinan-6-one, a crucial intermediate for obtaining the desired ketomorphinans of unnatural configuration. Asymmetric reduction of a 3,4-dihydroisoquinoline intermediate with a complex of sodiumborohydride with a proline derivative derived from natural S-proline has afforded the desired optically active tetrahydroisoquinoline of S-configuration. The original synthesis developed with racemic material will now be extended to the optically active S-enantiomer.